The present invention relates to a method for answering a telephone call coming to a mobile terminal in a situation where there is a packet-switched connection active in the mobile terminal, into which mobile terminal at least one reference item can be saved, and in which method a reception step is carried out, in which step information about the incoming call is received to the mobile terminal. The invention also relates to a mobile terminal, which comprises means for answering an incoming call in a situation where there is a packet-switched connection active in the mobile terminal, which mobile terminal comprises means for saving at least one reference item, and means for receiving information associated with the incoming call. Furthermore, the invention relates to a data transfer system comprising means for establishing a packet-switched connection between a mobile communication network and a mobile terminal, means for initiating a telephone call between the mobile communication network and the mobile terminal, means for associating at least one identifier with the telephone call, and means for saving at least one reference item, and which mobile terminal comprises means for answering an incoming call in a situation where a packet-switched connection is active in the mobile terminal.
The possibility to use packet-switched connections in addition to the common circuit-switched connections is being developed for mobile communication systems, such as the GSM system. A General Packet Radio Service (GPRS service) is being developed to the GSM mobile communication system for implementing packet-switched connections. The GPRS service enables, among other things, the use of the Internet Protocol and the X.25 data transfer protocol, short message service (SMS), e-mail transmission and wireless application protocol (WAP) applications. A packet-switched data transfer connection like this enables a data transmission method, which is more efficient than a circuit-switched connection, and which is especially suitable for asynchronic data transfer, because in a packet-switched connection the resources of the mobile communication system are not allocated for the duration of the whole connection, but only for the time required for the transmission of the packets. As a contrast to this, in a circuit-switched connection the connection is allocated for the whole time when the connection is active. By means of the packet-switched connection, the user of a mobile station can, for instance, keep an e-mail application activated all the time, whereby the user immediately detects an incoming e-mail message. Because the packet-switched connection allocates resources only according to need, it may also offer lower cost of telephone calls compared to the use of a circuit-switched connection.
The GSM standard 03.60 version 6.2.0 chapter 5.4.5 presents three modes of operation for a mobile station of the GPRS system: class A, class B and class C. Mobile stations can be divided into these classes according to the types of packet network properties implemented in them. Mobile stations of class A can use the GPRS services and other GSM services simultaneously. Mobile stations of class B can monitor the signals of the GPRS network and the control channel of the GSM network simultaneously, but they can use only either GPRS services or GSM services simultaneously. Mobile stations of class C can use a circuit-switched connection and a packet-switched GPRS connection, but not simultaneously.
In practice, a mobile station of class B can receive pagings associated with initiating a circuit-switched connection even when the mobile station is using GPRS services, e.g. has an active packet-switched connection. Then the mobile station can receive a CS paging message notifying of an incoming call, for instance, but it cannot operate in a circuit-switched and a packet-switched connection simultaneously. Then if a message associated with a circuit-switched connection arrives in the mobile station, the packet-switched connection is set in a suspended mode for the duration of the reception of the message and a possible circuit-switched connection, until the circuit-switched connection has been terminated. In an ideal situation this means that the mobile station can switch its mode between a packet-switched connection and a circuit-switched connection, and after the switching resume the mode of operation in which the mobile station was when the interruption arrived. In practice, however, it has been found that applications using a packet-switched connection, such as e-mail or an FTP application used for file transfer, are disconnected even during a relatively short interruption. An interruption like this can be caused even by a break of a few seconds, such as signalling a circuit-switched telephone call to a level which enables alerting for the call.
One way of preventing the applications from being disconnected is to disable all circuit-switched call attempts during a packet-switched connection. Then, however, telephone calls which the user would like to receive even during a packet-switched connection are also disabled.
Another possibility is that the user can select whether to receive the incoming call or not. In the modern mobile stations it is possible to show information about the caller, such as the Caller Line Identity (CLI), which shows the calling number. Then the user can see from whom the call is coming and make his/her decision on the basis of that. However, this arrangement has the drawback that the time that passes from the arrival of the call signal to the decision about reception can be so long that the active application using a packet-switched connection can stop running.
It is an objective of the present invention to provide a method and a system in which it is possible to establish a circuit-switched connection during a packet-switched connection, when required. The invention is based on the idea that at least a first and a second priority class is specified, and a telephone number is classified as belonging to either of the priority classes, whereby, if the request to establish a circuit-switched connection comes from a telephone number belonging to the first priority class, the circuit-switched connection is established, but in other cases the circuit-switched connection is not established. The method according to the present invention is characterised in that it comprises at least the following steps:
an examination step, in which the information received about a telephone call is examined in order to find at least one item of identification information, and to find out if whether reference items have been saved in the mobile terminal, whereby if at least one reference item has been saved, a comparison step is performed in the method, wherein said at least one reference item and said at least one item of identification information found in the examination step are compared, and
a decision step in which the decision about answering the phone call is made, and which decision is based on the comparison performed in said comparison step, if the comparison step was carried out.
The mobile terminal according to the present invention is characterised in that it comprises at least:
examination means for finding at least one item of identification information from the information received,
comparison means for comparing at least one reference item with the at least one item of identification information discovered in the examination means and for producing a comparison result, and
decision means for making the decision about answering the phone call on the basis of the comparison result produced by the comparison means.
A data transfer system according to the present invention is characterised in that it comprises at least:
examination means for finding at least one item of identification information from the information received in the mobile terminal,
comparison means for comparing at least one reference item with the at least one item of identification information discovered in the examination means and for producing a comparison result, and
decision means for making the decision about answering the phone call in the mobile terminal on the basis of the comparison result produced by the comparison means.
The present invention provides important advantages. When the method according to the invention is applied, disconnection of the packet-switched connection can be avoided especially in situations where the request to initiate a circuit-switched connection comes from a telephone number classified to a lower priority group. In that case, the user is not disturbed, either, because no ringing tone is produced in these situations. However, the user can define important telephone numbers, from which all incoming calls are connected regardless of whether the user has an active packet-switched connection or not. In a preferred embodiment of the invention, even in these situations the user can be given an opportunity to decide whether to receive the call or not. When the packet-switched connection is not interrupted when less important phone calls are coming, the packet-switched connection is not as likely to be disconnected as in the prior art solutions. Thus the user can specify in advance from which telephone numbers interruptions to the packet-switched connection are allowed.
In a method according to another preferred embodiment of the invention, the caller can, when required, specify whether the call is connected to the receiving number even in a situation that the receiver has an active packet-switched connection. In this arrangement, passwords or other identifiers can be used, if required, to prevent unauthorised interruptions of the packet-switched connection.